Explosions and fire incidents involving portable plastic gasoline containers manufactured for consumer use are known to occur frequently and are verified in databases, engineering literature, legal briefs, and newspapers. This project studied such incidents and presents findings from a comprehensive test program documenting conditions under which such incidents occur. Factors controlling resultant vapor headspace compositions and headspace ignitions and/or explosion occurrences include the following: mass of gasoline in relation to a particular container size, ambient temperature, and ''age'' of stored gasoline samples. Experimental results also demonstrated the effectiveness of flame arrestors to eliminate risk of explosion.